User error: "0" is an invalid render array key in Drupal\Core\Render\Element::children()

Steps to reproduce

1. Install Drupal 8.8.1
2. drush en -y media_library
3. Create media type "Remote video" with these settings →
4. Create some CT with a field making use of Media Library and allowing media type "Remote video"
5. In node form, click on field to open Media Library modal
6. If you have multiple media types, make sure you click on "Remote video" tab in modal

Current result

• DBlog logs :

• User error: "0" is an invalid render array key in Drupal\Core\Render\Element::children() (line 97 of /var/www/html/web/core/lib/Drupal/Core/Render/Element.php) #0 /var/www/html/web/core/includes/bootstrap.inc(596): _drupal_error_handler_real(256, '"0" is an inval...', '/var/www/html/w...', 97, Array) #1 [internal function]: _drupal_error_handler(256, '"0" is an inval...', '/var/www/html/w...', 97, Array) #2 /var/www/html/web/core/lib/Drupal/Core/Render/Element.php(97): trigger_error('"0" is an inval...', 256) #3 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(402): Drupal\Core\Render\Element::children(Array, false) #4 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(444): Drupal\Core\Render\Renderer->doRender(Array) #5 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(444): Drupal\Core\Render\Renderer->doRender(Array) #6 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(444): Drupal\Core\Render\Renderer->doRender(Array) #7 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(200): Drupal\Core\Render\Renderer->doRender(Array, false) #8 /var/www/html/web/core/lib/Drupal/Core/Template/TwigExtension.php(501): Drupal\Core\Render\Renderer->render(Array) #9 /var/www/html/web/sites/default/files/php/twig/5dfb4cb1a9345_media-library-wrapper.htm_f_JYNvTTrDG9miX3e2bneaS03/H_KnDp_1rc6iXO_SkhJbWRntrV_j5n1nyTPPE_UaW3g.php(64): Drupal\Core\Template\TwigExtension->escapeFilter(Object(Drupal\Core\Template\TwigEnvironment), Array, 'html', NULL, true) #10 /var/www/html/vendor/twig/twig/src/Template.php(455): __TwigTemplate_b883481b98094281f15633095b8d30955b6dbe2479a50f1c3d2fd27f11228de9->doDisplay(Array, Array) #11 /var/www/html/vendor/twig/twig/src/Template.php(422): Twig\Template->displayWithErrorHandling(Array, Array) #12 /var/www/html/vendor/twig/twig/src/Template.php(434): Twig\Template->display(Array) #13 /var/www/html/web/core/themes/engines/twig/twig.engine(64): Twig\Template->render(Array) #14 /var/www/html/web/core/lib/Drupal/Core/Theme/ThemeManager.php(384): twig_render_template('core/themes/cla...', Array) #15 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(431): Drupal\Core\Theme\ThemeManager->render('media_library_w...', Array) #16 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(200): Drupal\Core\Render\Renderer->doRender(Array, true) #17 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(144): Drupal\Core\Render\Renderer->render(Array, true) #18 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(573): Drupal\Core\Render\Renderer->Drupal\Core\Render\{closure}() #19 /var/www/html/web/core/lib/Drupal/Core/Render/Renderer.php(145): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure)) #20 /var/www/html/web/core/lib/Drupal/Core/Ajax/CommandWithAttachedAssetsTrait.php(36): Drupal\Core\Render\Renderer->renderRoot(Array) #21 /var/www/html/web/core/lib/Drupal/Core/Ajax/OpenDialogCommand.php(135): Drupal\Core\Ajax\OpenDialogCommand->getRenderedContent() #22 /var/www/html/web/core/lib/Drupal/Core/Ajax/AjaxResponse.php(43): Drupal\Core\Ajax\OpenDialogCommand->render() #23 /var/www/html/web/core/modules/media_library/src/Plugin/Field/FieldWidget/MediaLibraryWidget.php(776): Drupal\Core\Ajax\AjaxResponse->addCommand(Object(Drupal\Core\Ajax\OpenModalDialogCommand)) #24 [internal function]: Drupal\media_library\Plugin\Field\FieldWidget\MediaLibraryWidget::openMediaLibrary(Array, Object(Drupal\Core\Form\FormState), Object(Symfony\Component\HttpFoundation\Request)) #25 /var/www/html/web/core/lib/Drupal/Core/Form/FormAjaxResponseBuilder.php(69): call_user_func_array(Array, Array) #26 /var/www/html/web/core/lib/Drupal/Core/Form/EventSubscriber/FormAjaxSubscriber.php(109): Drupal\Core\Form\FormAjaxResponseBuilder->buildResponse(Object(Symfony\Component\HttpFoundation\Request), Array, Object(Drupal\Core\Form\FormState), Array) #27 [internal function]: Drupal\Core\Form\EventSubscriber\FormAjaxSubscriber->onException(Object(Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent), 'kernel.exceptio...', Object(Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher)) #28 /var/www/html/web/core/lib/Drupal/Component/EventDispatcher/ContainerAwareEventDispatcher.php(111): call_user_func(Array, Object(Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent), 'kernel.exceptio...', Object(Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher)) #29 /var/www/html/vendor/symfony/http-kernel/HttpKernel.php(227): Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch('kernel.exceptio...', Object(Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent)) #30 /var/www/html/vendor/symfony/http-kernel/HttpKernel.php(79): Symfony\Component\HttpKernel\HttpKernel->handleException(Object(Drupal\Core\Form\FormAjaxException), Object(Symfony\Component\HttpFoundation\Request), 1) #31 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/Session.php(57): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #32 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(47): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #33 /var/www/html/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(106): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #34 /var/www/html/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(85): Drupal\page_cache\StackMiddleware\PageCache->pass(Object(Symfony\Component\HttpFoundation\Request), 1, true) #35 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(47): Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #36 /var/www/html/web/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(52): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #37 /var/www/html/vendor/stack/builder/src/Stack/StackedHttpKernel.php(23): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #38 /var/www/html/web/core/lib/Drupal/Core/DrupalKernel.php(694): Stack\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #39 /var/www/html/web/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request)) #40 {main}.
  

Expected result

• Displaying Media Library modal should not throw any error

Todo

• Debug and fix